However the Greens, after a vigorous internal debate, today ditched their support when it became clear the revenue from the fuel tax would not be used to fund public transport alternatives to the family car, and in fact could encourage greater car use by building new roads.

“This fuel excise increase is not a tax on pollution, it’s a tax on families who have no access to public transport,” Greens Leader Christine Milne said today.

She said the Government had a “hypocritical and inconsistent approach to reducing carbon pollution” and would not negotiate on changes to its plans to send all revenue from excise to the roads program.

“We also have zero confidence in the Prime Minister’s word, who says one thing and does another. The Greens will therefore vote down the package as a whole with no negotiation,” she said.

No detailed modelling of the effect the excise — frozen for more than a decade — would have on family expenses has been made public. Mr Abbott has said it would, in the first year, add 40 cents a week to the average family’s expenses although another calculation has put this at 55 cents.

A key issue in the Greens’ decision was that big mining companies would not have to pay more for diesel used off-road.

“The Prime Minister doesn’t get it. Fuel excise should be about moving away from pollution, but Tony Abbott just sees it as a way of raising revenue by taxing families who have no access to public transport,” Senator Milne said.

“The Greens support taking pollution but it makes absolutely no sense to put the money into roads. That will increase congestion and make it harder for families in places with little or no public transport.

“Big miners should pay more for fuel just like everyone else. Why should Gina Rinehart get cheap fuel when ordinary commuters suffer?”